[ARM] 4902/1: [AT91] SAM9/CAP9 memory controller header

The AT91CAP9 processor includes the same Static Memory Controller
(SMC) peripheral as the SAM9 processors, but replaces the SDRAM
Controller with a DDR/SDR Controller (DDRSDRC).

This patch splits the existing
include/asm-arm/arch-at91/at91sam926x_mc.h into at91sam9_sdramc.h and
at91sam9_smc.h.
It also adds an at91cap9_ddrsdr.h for the DDRSDRC controller.

Signed-off-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>